As women get older their risk for having a baby with a change in chromosome number increases. There is no magic age at which a woman goes from no risk to high risk. However, at age 35 the risk is considered high enough to offer some standard testing options that we will discuss today.

2 are diagnostic tests (CVS and amniocentesis) which will tell you with nearly 99.7% certainty if the fetus has one of the chromosomal changes discussed and almost 100% certainty whether the fetus has CF

Ultrasound will help in determining the overall development of the major organs and can show some birth defects (may show fetal echogenic bowel and/or dilated bowel which can be an indication of CF)

The little fingerlike projections of the placenta that are sampled are called chorionic villi

The villi are derived from the same original cells as the fetus so these cells should have the same genes and chromosomes as the fetus and we can look at the chromosomes in these cells and detect the chromosomal abnormalities discussed earlier

It is a simple medical procedure that is usually performed after 15 weeks gestation that is used to rule out many chromosomal abnormalities including the ones we just discussed that you are at increased risk for

A small sample of the amniotic fluid that surrounds the baby is taken

Within the fluid are skin cells that have been sloughed off by the baby.

These cells can be grown in a lab and then the chromosomes can be looked at

.5% additional risk for pregnancy loss with amnio (1 out of every 200 women who have an amnio will have a miscarriage that is due directly to the procedure) 1% with CVS These risks are above the baseline risk of miscarriage that all women have.

Routine amnio is not associated with increased risks of birth defects in the fetus

Scarring of the baby is possible but is thought to be very uncommon

Extremely low risk of uterine infection

Some studies reported a possible risk of limb defects with CVS while other studies have not. Most of the defects were noted if the procedure was performed before 10 weeks because the limbs develop between 4-10 wks. If there is an increased risk it is about 1 in 3000.

Risks are lower if the physician is highly experienced

There is a very small chance of lab error and the need to repeat the procedure

Abdomen is cleansed and xylocaine injection is given to numb the upper layers (similar to shot given at the dentist)

Using ultrasound as visual guidance, spinal needle is guided through the abdominal wall, uterine wall, and into the placenta

Once in place a syringe is attached to supply suction

While suction is supplied the needle is moved back and forth through the placenta

After sample is obtained it is viewed to make sure there is enough and another sample is not required

Sample is then placed in a tube of tissue culture medium and sent to a lab for testing

There is a wide range of responses when it comes to how women report the procedure felt. When the needle is inserted it may burn for a few seconds. Women report everything from mild cramping to painful, heavy cramping.

Can be used to detect any genetic condition for which there is a sufficient sequence information

Can detect common aneuploidies and translocations

As many as 40 PGD centers have been established in 17 countries

By this time, these centers performed approximately 3,000 clinical cycles, resulting in more than 500 pregnancies (over 20% pregnancy rate), and the birth of nearly 300 healthy children.

More than two thirds of these clinical cycles were performed in USA, from which the largest number (1,200 cycles) was contributed by RGI. This resulted in 250 pregnancies and birth of approximately 200 healthy children

At present, RGI (Chicago) is the only center in the world offering Preimplantation Diagnosis by sampling the first and second polar bodies.

he first polar body is discarded during oocyte maturation, prior to fertilization and contains one set of duplicated chromosomes

the second polar body is discarded after fertilization and contains one set of chromatids

test the polar bodies for genetic disease to determine if egg has mutation

offered to couples who are known carriers of genetic diseases detectable by DNA analysis